Blackfacing a 74' Bassman 10

[tibbar6]

Hello, I just recently scored a bassman 10 off CG for only 200$ with the hopes of restoring it and changing back to AA864 specs.
It seems like someone altered the bias resistor with out changing the bias balanced circuit. The power tubes were blown and all of the electrolytic caps are still original and need replacing.

I noticed that this is a rather strange model, it has a factory 'middle' control and it seems to be a bit different than most schematics I can find online. There are only 5 wires coming from the transformer opposed to the normal 7 and there is also factory installed 2.2k 7W resistor wired between the standby switch and the 70 uf filter caps. I cant find any schematic with either of these changes. Is the amp really benefiting from this resistor? should it be removed and jumpered?

You can see the 2.2k resistor as well as the transformer leads and the altered bias resistor here http://i1168.photobucket.com/albums/...pstsrlfvuy.jpg

Also check out the funky tolex it came with! http://i1168.photobucket.com/albums/...ps6xclltgy.jpg

Thanks

-A

[52 Bill]

I noticed that this is a rather strange model, it has a factory 'middle' control and it seems to be a bit different than most schematics I can find online. There are only 5 wires coming from the transformer opposed to the normal 7 and there is also factory installed 2.2k 7W resistor wired between the standby switch and the 70 uf filter caps. I cant find any schematic with either of these changes. Is the amp really benefiting from this resistor? should it be removed and jumpered?

I don't understand the comment about only 5 wires coming out of the transformer. The output transformer? 5 wires are typical for most Fender amps with no additional speaker outputs and no screen taps.

The schematic shows a 2K2 7Watt resistor used in place of the typical filter choke. Are you sure that the resistor is on the supply side of the standby switch and not on the screen grid side?

[pdf64]

Hello, I just recently scored a bassman 10 off CG for only 200$ with the hopes of restoring it and changing back to AA864 specs...

I'm sure you can get a nice amp out of it, but it may not be a very suitable candidate to be turned into an AA864.
The PT puts out a higher HT voltage, as noted there's no choke, and I seem to remember it being reported that the OT is less beefy that that of the 60s bassman.
Also it is missing a tube.
I think it's intended to be more suited to be a clean bass amp, rather than an overdriven guitar amp.
It could be a very good clean amp, eg as a pedal platform.

[Justin Thomas]

You could sacrifice a channel to get the extra tube, but like others said, I'd put it back to stock and sell it for what it is, and use the money to get a Bassman head. Anything from an AA165 => Bassman 50 non-Master Volume should do nicely. Or, a kit - they make BF Bassman kits now.

As it is, I'd love to have a 50W 4x10 clean bass amp... but I'm broke.

Justn

PS: as it's basically a low-power Bassman 100, it'll crunch nicely as is. Trust me. Can <you> stand the volume?

[Valvehead]

I just re-capped a Bassman 10 and it had that same 2.2k 5 watt .

[drewl]

I think they sound pretty good when functioning properly.
An old bandmate had one I tined up.

Not a high gainer, but a good sounding amp.

[Leo_Gnardo]

Also check out the funky tolex it came with! http://i1168.photobucket.com/albums/...ps6xclltgy.jpg

Ow that made my eyes hurt! Waaaay funky all right. Now you MUST make this amp work right. Belongs onstage with David Lindley.

FWIW I've worked on a couple of these & they do turn out well. The cabs seem a bit loosely made, one was just about falling apart but the amp owner liked his Bassman 10 so much he threw down to have a new, solidly made cabinet constructed.